ECU problems with 1.9 DCI 04 Megane Scenic?

Ive got same problem as most "check ignition"....air con doesnt work even though its holding gas....and its now been intermittently loosing power, as though the turbo isnt working. When I switch it off and re-start it works fine for a while. Now things have gone bad to worse, no power, sounds like a bag of spanners chucking out masses of smoke? Is this an ECU problem? I dont really fancy taking it to Renault.

Nik